Metabolism of α-Glycerol Phosphate in Human Adipose Tissue in Obesity1

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Abstract
1. 1. Experiments were carried out to examine the possibility that a metabolic defect underlies the development of some types of obesity in man. Glycerol phosphate, which is an obligatory acyl acceptor for lipogenesis in human adipose tissue, is formed by a cytoplasmic L-aglycerophosphate dehydrogenase whose activity in adipose tissue of lean and obese patients was, respectively: 36 ± 4 (7)3 and 20 ± 2 (7) mμxmoles NADH/min/mg protein (p <.01). 2. 2. α-Glycerol phosphate can be oxidized by mitochondria of human adipose tissue at a rate of: 14.2 ± 2.2 (8) and 6.9 ± 1.8 (7) μl O2/30 min/mg protein in lean and obese patients, respectively (p < 0.02). Since α-glycerol phosphate is present oxidation of α-glycerol phosphate by mitochondria contributes in part to the development of obesity by increasing the supply of α-glycerol phosphate for lipogenesis. 3. 3. Not all obese patients displayed this mitochondrial deficiency. Three patients were studied in whom an intracranial lesion was possibly responsible for the weight gain. Comparisons of the rates of mitochondrial oxidation of α-glycerol phosphate between this group and 3 obese controls adjacent in the series were: 6.5 ± 2.1 (3) and 2.7 ± 1.5 (3) (p > 0.1). These values suggest that the metabolism of α-glycerol phosphate may be different in the former type of obesity.